Date   

Re: Iwasu scopes

Terry Gray
 

The only Iwatsu's that I am familiar with are the models SS-7840H(470MHz) and the SS-7840(400Mhz).  Seem to be really great scopes when you get their power supplies repaired.                  Terry


From: Jerry Barr
To: "TekScopes@..."
Sent: Wednesday, April 24, 2013 9:18 PM
Subject: Re: [TekScopes] Iwasu scopes

 
wanna say 5711 with dmm and counter
 
Jerry KJ6NTL
From: Terry Gray
To: "TekScopes@..."
Sent: Wednesday, April 24, 2013 6:35 PM
Subject: Re: [TekScopes] Iwasu scopes
 
Which model?

From: Jerry
To: TekScopes@...
Sent: Wednesday, April 24, 2013 3:26 PM
Subject: [TekScopes] Iwasu scopes
 
anyone here ever work on a iwasu scope



Re: Iwasu scopes

Jerry Barr
 

wanna say 5711 with dmm and counter
 
Jerry KJ6NTL

From: Terry Gray
To: "TekScopes@..."
Sent: Wednesday, April 24, 2013 6:35 PM
Subject: Re: [TekScopes] Iwasu scopes
 
Which model?

From: Jerry
To: TekScopes@...
Sent: Wednesday, April 24, 2013 3:26 PM
Subject: [TekScopes] Iwasu scopes
 
anyone here ever work on a iwasu scope


Re: Iwasu scopes

Terry Gray
 

Which model?


From: Jerry
To: TekScopes@...
Sent: Wednesday, April 24, 2013 3:26 PM
Subject: [TekScopes] Iwasu scopes

 
anyone here ever work on a iwasu scope




Re: Tek 2235 No Horizontal B sweep.

vdonisa
 

also since you elected to input the signal through channel 2, make sure you select the trigger input ("A&B Source") as channel 2.

--- In TekScopes@..., "vdonisa" <vdonisa@...> wrote:

With the "mode" selector in the "ALT" position, did you turn the "B delay" and "B trigger level" until you could see a highlighted portion of the waveform?

If you don't see a highlighted segment, then when you'll switch "mode" to B you won't see anything.

With the controls set as above, do you see a second waveform on the CRT? If not, you need to adjust "B intensity" and "A/B SWP SEP" until you can see it.

Now you can finally turn "mode"to B position, the main waveform will disappear and the second one will stay.

Any of the 4 controls mentioned can make it disappear, so the best thing is to first make sure that you see it with Mode in Alt position.

--- In TekScopes@..., "acousticbruce" <acousticbruce@> wrote:

You know I am going to hit myself if it was because I didnt set the B sec/div. I really thought I tested this because I do understand what B mode is for. So I will respond again soon with what I find.



--- In TekScopes@..., "vdonisa" <vdonisa@> wrote:

You can beat me but I can't figure what the purpose of your test is. That control is used to provide a "magnifier" of a small segment of the main waveform. The normal way I use it is to pull the time base knob and rotate it CW, with the "Mode" button on "ALT". At that moment a segment of the existing waveform is displayed "intensified" (brighter) and the brighter segment is shown magnified as a second waveform. Using the B trigger level and B delay time controls, you can move the "intensified" area along the main waveform to select which particular area you want to magnify.
Switching the "mode" control to "B" will display only the "magnified" area (the main waveform disappears from the screen).

--- In TekScopes@..., "acousticbruce" <acousticbruce@> wrote:

That control did not fix the problem. I did double check and try it fully clockwise among other positions. I really think it is a problem with the scope. I am open to ideas.

--- In TekScopes@..., David <davidwhess@> wrote:

Check the setting of the B trigger level control (top right corner
below VAR HOLDOFF). It can either be set to "runs after" or "triggers
after". In most cases you want it set all the way clockwise to "runs
after".

On Wed, 24 Apr 2013 16:36:28 -0000, "acousticbruce"
<acousticbruce@> wrote:

I have this 2235 that seems to be working for well on everything except the horizontal B sweep. What I did is put it in B mode and you can see to the left of the CRT some light. So I moved the horizontal position until you saw a possible triggered wave. I slowed the time down and you can see the beam moving up and down as suspected. I figured it is not sweeping. I am unsure if it will trigger either because I need it to sweep.

Here is a youtube video of me getting right to the point and showing this issue.

http://youtu.be/IfTkgZURFi0

This video gets right to the point and is short. I show a working sweep in A horizontal then flip to B horizontal.

What do you guys think?


Re: Tek 2235 No Horizontal B sweep.

vdonisa
 

With the "mode" selector in the "ALT" position, did you turn the "B delay" and "B trigger level" until you could see a highlighted portion of the waveform?

If you don't see a highlighted segment, then when you'll switch "mode" to B you won't see anything.

With the controls set as above, do you see a second waveform on the CRT? If not, you need to adjust "B intensity" and "A/B SWP SEP" until you can see it.

Now you can finally turn "mode"to B position, the main waveform will disappear and the second one will stay.

Any of the 4 controls mentioned can make it disappear, so the best thing is to first make sure that you see it with Mode in Alt position.

--- In TekScopes@..., "acousticbruce" <acousticbruce@...> wrote:

You know I am going to hit myself if it was because I didnt set the B sec/div. I really thought I tested this because I do understand what B mode is for. So I will respond again soon with what I find.



--- In TekScopes@..., "vdonisa" <vdonisa@> wrote:

You can beat me but I can't figure what the purpose of your test is. That control is used to provide a "magnifier" of a small segment of the main waveform. The normal way I use it is to pull the time base knob and rotate it CW, with the "Mode" button on "ALT". At that moment a segment of the existing waveform is displayed "intensified" (brighter) and the brighter segment is shown magnified as a second waveform. Using the B trigger level and B delay time controls, you can move the "intensified" area along the main waveform to select which particular area you want to magnify.
Switching the "mode" control to "B" will display only the "magnified" area (the main waveform disappears from the screen).

--- In TekScopes@..., "acousticbruce" <acousticbruce@> wrote:

That control did not fix the problem. I did double check and try it fully clockwise among other positions. I really think it is a problem with the scope. I am open to ideas.

--- In TekScopes@..., David <davidwhess@> wrote:

Check the setting of the B trigger level control (top right corner
below VAR HOLDOFF). It can either be set to "runs after" or "triggers
after". In most cases you want it set all the way clockwise to "runs
after".

On Wed, 24 Apr 2013 16:36:28 -0000, "acousticbruce"
<acousticbruce@> wrote:

I have this 2235 that seems to be working for well on everything except the horizontal B sweep. What I did is put it in B mode and you can see to the left of the CRT some light. So I moved the horizontal position until you saw a possible triggered wave. I slowed the time down and you can see the beam moving up and down as suspected. I figured it is not sweeping. I am unsure if it will trigger either because I need it to sweep.

Here is a youtube video of me getting right to the point and showing this issue.

http://youtu.be/IfTkgZURFi0

This video gets right to the point and is short. I show a working sweep in A horizontal then flip to B horizontal.

What do you guys think?


Re: Looking for Tektronix 419 scopes and parts

altairjump
 

Sorry typo I'm looking for 519 scopes and parts.

--- In TekScopes@..., David DiGiacomo <daviddigiacomo@...> wrote:

On Wed, Apr 24, 2013 at 1:19 PM, altairjump <altairjump@...> wrote:
Hi,
I'm looking for Tektronix 419 oscilloscopes and parts. Also looking for a maintanence manual( I found the operations manual on BAMA) The scopes can be dead or alive for I need parts to rebuild two I have. Please let me know if anyone has any. I will travel to your location if you have complete scopes.
Do you mean 491, 519, or ????


Re: OT: the capacitor curse

Daniel Wolstenholme
 

A while ago I bought a Xerox WorkCentre M20i printer/copier at an equipment auction for a company that went under. It looked like it should have been working, as it even had faxes still sitting on it when I picked it up from some of the company's creditors and other bankruptcy-related documents. However, when I brought it home it was completely dead. I diagnosed it as a failed power supply. Replacements were very expensive (more than I paid for the printer at any rate), so I just took apart the PS, ordered replacement capacitors at Mouser for about $10-15, and installed them. It worked fine after that.

Dan

--- In TekScopes@..., "vdonisa" <vdonisa@...> wrote:
It looks to me that it is mostly american brands that tend to use poor quality components in their devices, and it's not the engineers at fault (they seem to understand what they're doing, the designs are largely correct). It must be something they teach these days in the "business schools" and it seems to be wrong - anyone who's applying that "science" is having huge problems - from Wall Street to Dell not to mention what happened to Sony while led by an imported-from-US CEO.


Re: HV Multiplier defective in 7603?

raymonddompfrank <r.domp.frank@...>
 

Thanks, Don, that's what I had in mind and I have already been looking for a suitable R until I just realized that there are several on this very same thick film device... Should be an easy thing if they're all ok.

Raymond

--- In TekScopes@..., Don Black <donald_black@...> wrote:

You can measure the 24.5 M resistor by putting a lower value resistor in
parallel and then measuring. If it's completely open you'll just get the
value of the parallel resistor but if it's OK the resistance will be
lower. Then you can calculate the value of the 24.5, there are little
programs on the net to do it for you. I'd suggest using a 10 Meg in
parallel if your meter can go that high, otherwise a 1 Meg.

Don Black.

On 25-Apr-13 6:30 AM, raymonddompfrank wrote:

My idea about loading the circuit came from the thought that the
multiplier input would see a peak-detected DC voltage that had to see
some load to discharge. Nonsense, of course. My excuse is that it was
at 7am this morning and I had been working all day and night (not on
this problem).
Just pulled Q1201. Cathode voltage goes down to far below 2KV so
Q1206, Q1214 and associated circuitry could well be ok. Looking at the
circuitry driving Q1201 now (R1245 etc). R1245B could be open but I
can't easily measure 24.5Mohm.

Next would be the Grid Bias circuitry.

Cathode filament is not open (2 Ohm across P1275 pins 1, 2).

--- In TekScopes@... <mailto:TekScopes%40yahoogroups.com>,
David <davidwhess@> wrote:

I will not say that is impossible but if I designed it, the cathode
voltage regulation would function correctly with or without the high
voltage multiplier attached. I think the load on the 6.3 volt AC
heater supply which also comes from T1225 would overwhelm any effect
from the high voltage multiplier load.

You might want to check that the CRT heater is not open. I think you
said earlier it is not shorted to the cathode.

The error amplifier design Tektronix used seems rather unwieldy to me.
I wish they had marked the typical operating voltages on the schematic
but maybe there was too much variation for that to be useful.

The 7613 and 7623 use the same basic design while the 7623A and 7633
use a single ended oscillator driving the transformer instead of a
push-pull oscillator. I looked over the schematics for all four of
those and none provided any insight into the typical operating values.

On Wed, 24 Apr 2013 17:11:45 -0000, "raymonddompfrank"
<r.domp.frank@> wrote:

David,
I thought that the multiplier was needed to allow regulation to
work, so -4KV would be reasonable without any load.
Of course, load by a healthy multiplier and CRT would be minimal,
so you maybe right, also re. destruction of the multiplier as a
consequence of the -4KV.
I will take a look at the feedback/regulation circuit.

Thanks for helping me on my way.

With regard to encapsulating the discrete HV components: What you
describe is what I had in mind once the circuit would work "supended
in the air", plus thanks for reminding me to get rid of air bubbles.

Raymond

--- In TekScopes@...
<mailto:TekScopes%40yahoogroups.com>, David <davidwhess@> wrote:

Concerning your point 4, with the presumably bad high voltage
multiplier disconnected, shouldn't the high voltage test point settle
at -2975 volts?

That makes me think something failed in the regulation circuit built
around Q1201, Q1206, and Q1214 including feedback divider R1245.

If the high voltage regulator ran away then maybe it damaged the high
voltage multiplier instead of the reverse.

As to building one with discrete parts, that is what I would do. The
esoteric thing that comes to mind other than standard high voltage
construction methods is the use of a vacuum to remove air from any
potting mixture. I would build the circuit supported in air by its
three external connections without using perforated board and
then pot
it.


Re: HV Multiplier defective in 7603?

Don Black <donald_black@...>
 

You can measure the 24.5 M resistor by putting a lower value resistor in parallel and then measuring. If it's completely open you'll just get the value of the parallel resistor but if it's OK the resistance will be lower. Then you can calculate the value of the 24.5, there are little programs on the net to do it for you. I'd suggest using a 10 Meg in parallel if your meter can go that high, otherwise a 1 Meg.

Don Black.

On 25-Apr-13 6:30 AM, raymonddompfrank wrote:
 

My idea about loading the circuit came from the thought that the multiplier input would see a peak-detected DC voltage that had to see some load to discharge. Nonsense, of course. My excuse is that it was at 7am this morning and I had been working all day and night (not on this problem).
Just pulled Q1201. Cathode voltage goes down to far below 2KV so Q1206, Q1214 and associated circuitry could well be ok. Looking at the circuitry driving Q1201 now (R1245 etc). R1245B could be open but I can't easily measure 24.5Mohm.

Next would be the Grid Bias circuitry.

Cathode filament is not open (2 Ohm across P1275 pins 1, 2).

--- In TekScopes@..., David wrote:
>
> I will not say that is impossible but if I designed it, the cathode
> voltage regulation would function correctly with or without the high
> voltage multiplier attached. I think the load on the 6.3 volt AC
> heater supply which also comes from T1225 would overwhelm any effect
> from the high voltage multiplier load.
>
> You might want to check that the CRT heater is not open. I think you
> said earlier it is not shorted to the cathode.
>
> The error amplifier design Tektronix used seems rather unwieldy to me.
> I wish they had marked the typical operating voltages on the schematic
> but maybe there was too much variation for that to be useful.
>
> The 7613 and 7623 use the same basic design while the 7623A and 7633
> use a single ended oscillator driving the transformer instead of a
> push-pull oscillator. I looked over the schematics for all four of
> those and none provided any insight into the typical operating values.
>
> On Wed, 24 Apr 2013 17:11:45 -0000, "raymonddompfrank"
> wrote:
>
> >David,
> >I thought that the multiplier was needed to allow regulation to work, so -4KV would be reasonable without any load.
> >Of course, load by a healthy multiplier and CRT would be minimal, so you maybe right, also re. destruction of the multiplier as a consequence of the -4KV.
> >I will take a look at the feedback/regulation circuit.
> >
> >Thanks for helping me on my way.
> >
> >With regard to encapsulating the discrete HV components: What you describe is what I had in mind once the circuit would work "supended in the air", plus thanks for reminding me to get rid of air bubbles.
> >
> >Raymond
> >
> >--- In TekScopes@..., David wrote:
> >>
> >> Concerning your point 4, with the presumably bad high voltage
> >> multiplier disconnected, shouldn't the high voltage test point settle
> >> at -2975 volts?
> >>
> >> That makes me think something failed in the regulation circuit built
> >> around Q1201, Q1206, and Q1214 including feedback divider R1245.
> >>
> >> If the high voltage regulator ran away then maybe it damaged the high
> >> voltage multiplier instead of the reverse.
> >>
> >> As to building one with discrete parts, that is what I would do. The
> >> esoteric thing that comes to mind other than standard high voltage
> >> construction methods is the use of a vacuum to remove air from any
> >> potting mixture. I would build the circuit supported in air by its
> >> three external connections without using perforated board and then pot
> >> it.
>



Re: HV Multiplier defective in 7603?

raymonddompfrank <r.domp.frank@...>
 

David,
I had already replaced Q1201 after operating without it reduced cathode voltage a lot. No difference.

Also checked CR1244 and its (cathode) connection to +50V. Looks OK.
That's why I'd like to check R1245B as mentioned earlier but I have no easy way to measure directly. Guess I'll try putting something in parallel to get below 20MOhm, my meter's max. Guess I'll unsolder R2445 (thick film), 6 pins. I have the right equipment to pull solder away.

--- In TekScopes@..., David <davidwhess@...> wrote:

Both the high voltage multiplier and the cathode supply work off of
the peak voltage from T1225 but since the regulator only uses the
rectified and filtered cathode supply for feedback, it does not care
what the high voltage multiplier is doing unless it draws too much
power.

The high voltage and cathode voltage outputs are actually designed to
track pretty closely so the regulator indirectly controls the
acceleration voltage by regulating the cathode voltage because the
former needs to be stable for proper horizontal and vertical
calibration. Thinking about it now, I wonder if CR1244 is there to
roughly temperature compensate the diode voltage drops through the
high voltage multiplier. As the temperature goes up, the cathode
voltage will drop by roughly 120mV/Cdegrees (59.5 x 2 mV/Cdegrees)
which would be about 30mV/Cdegrees for each diode in the multiplier. I
am not sure that the post deflection accelerator voltage needs that
much accuracy but it would explain CR1244.

I would be really suspicious of Q1201. It only operates with
microamps of collector current so if it was suffering from high
leakage, that would explain the high voltage.

Another easy check would be the anode of CR1244 which should be +50.6
volts.

I just noticed that there is no cathode voltage adjustment. The 4
slot 7000 mainframes have a trimmer to adjust the cathode voltage.

On Wed, 24 Apr 2013 20:30:48 -0000, "raymonddompfrank"
<r.domp.frank@...> wrote:

My idea about loading the circuit came from the thought that the multiplier input would see a peak-detected DC voltage that had to see some load to discharge. Nonsense, of course. My excuse is that it was at 7am this morning and I had been working all day and night (not on this problem).
Just pulled Q1201. Cathode voltage goes down to far below 2KV so Q1206, Q1214 and associated circuitry could well be ok. Looking at the circuitry driving Q1201 now (R1245 etc). R1245B could be open but I can't easily measure 24.5Mohm.

Next would be the Grid Bias circuitry.

Cathode filament is not open (2 Ohm across P1275 pins 1, 2).


--- In TekScopes@..., David <davidwhess@> wrote:

I will not say that is impossible but if I designed it, the cathode
voltage regulation would function correctly with or without the high
voltage multiplier attached. I think the load on the 6.3 volt AC
heater supply which also comes from T1225 would overwhelm any effect
from the high voltage multiplier load.

You might want to check that the CRT heater is not open. I think you
said earlier it is not shorted to the cathode.

The error amplifier design Tektronix used seems rather unwieldy to me.
I wish they had marked the typical operating voltages on the schematic
but maybe there was too much variation for that to be useful.

The 7613 and 7623 use the same basic design while the 7623A and 7633
use a single ended oscillator driving the transformer instead of a
push-pull oscillator. I looked over the schematics for all four of
those and none provided any insight into the typical operating values.

On Wed, 24 Apr 2013 17:11:45 -0000, "raymonddompfrank"
<r.domp.frank@> wrote:

David,
I thought that the multiplier was needed to allow regulation to work, so -4KV would be reasonable without any load.
Of course, load by a healthy multiplier and CRT would be minimal, so you maybe right, also re. destruction of the multiplier as a consequence of the -4KV.
I will take a look at the feedback/regulation circuit.

Thanks for helping me on my way.

With regard to encapsulating the discrete HV components: What you describe is what I had in mind once the circuit would work "supended in the air", plus thanks for reminding me to get rid of air bubbles.

Raymond

--- In TekScopes@..., David <davidwhess@> wrote:

Concerning your point 4, with the presumably bad high voltage
multiplier disconnected, shouldn't the high voltage test point settle
at -2975 volts?

That makes me think something failed in the regulation circuit built
around Q1201, Q1206, and Q1214 including feedback divider R1245.

If the high voltage regulator ran away then maybe it damaged the high
voltage multiplier instead of the reverse.

As to building one with discrete parts, that is what I would do. The
esoteric thing that comes to mind other than standard high voltage
construction methods is the use of a vacuum to remove air from any
potting mixture. I would build the circuit supported in air by its
three external connections without using perforated board and then pot
it.


Re: HV Multiplier defective in 7603?

 

Both the high voltage multiplier and the cathode supply work off of
the peak voltage from T1225 but since the regulator only uses the
rectified and filtered cathode supply for feedback, it does not care
what the high voltage multiplier is doing unless it draws too much
power.

The high voltage and cathode voltage outputs are actually designed to
track pretty closely so the regulator indirectly controls the
acceleration voltage by regulating the cathode voltage because the
former needs to be stable for proper horizontal and vertical
calibration. Thinking about it now, I wonder if CR1244 is there to
roughly temperature compensate the diode voltage drops through the
high voltage multiplier. As the temperature goes up, the cathode
voltage will drop by roughly 120mV/Cdegrees (59.5 x 2 mV/Cdegrees)
which would be about 30mV/Cdegrees for each diode in the multiplier. I
am not sure that the post deflection accelerator voltage needs that
much accuracy but it would explain CR1244.

I would be really suspicious of Q1201. It only operates with
microamps of collector current so if it was suffering from high
leakage, that would explain the high voltage.

Another easy check would be the anode of CR1244 which should be +50.6
volts.

I just noticed that there is no cathode voltage adjustment. The 4
slot 7000 mainframes have a trimmer to adjust the cathode voltage.

On Wed, 24 Apr 2013 20:30:48 -0000, "raymonddompfrank"
<r.domp.frank@...> wrote:

My idea about loading the circuit came from the thought that the multiplier input would see a peak-detected DC voltage that had to see some load to discharge. Nonsense, of course. My excuse is that it was at 7am this morning and I had been working all day and night (not on this problem).
Just pulled Q1201. Cathode voltage goes down to far below 2KV so Q1206, Q1214 and associated circuitry could well be ok. Looking at the circuitry driving Q1201 now (R1245 etc). R1245B could be open but I can't easily measure 24.5Mohm.

Next would be the Grid Bias circuitry.

Cathode filament is not open (2 Ohm across P1275 pins 1, 2).


--- In TekScopes@..., David <davidwhess@...> wrote:

I will not say that is impossible but if I designed it, the cathode
voltage regulation would function correctly with or without the high
voltage multiplier attached. I think the load on the 6.3 volt AC
heater supply which also comes from T1225 would overwhelm any effect
from the high voltage multiplier load.

You might want to check that the CRT heater is not open. I think you
said earlier it is not shorted to the cathode.

The error amplifier design Tektronix used seems rather unwieldy to me.
I wish they had marked the typical operating voltages on the schematic
but maybe there was too much variation for that to be useful.

The 7613 and 7623 use the same basic design while the 7623A and 7633
use a single ended oscillator driving the transformer instead of a
push-pull oscillator. I looked over the schematics for all four of
those and none provided any insight into the typical operating values.

On Wed, 24 Apr 2013 17:11:45 -0000, "raymonddompfrank"
<r.domp.frank@...> wrote:

David,
I thought that the multiplier was needed to allow regulation to work, so -4KV would be reasonable without any load.
Of course, load by a healthy multiplier and CRT would be minimal, so you maybe right, also re. destruction of the multiplier as a consequence of the -4KV.
I will take a look at the feedback/regulation circuit.

Thanks for helping me on my way.

With regard to encapsulating the discrete HV components: What you describe is what I had in mind once the circuit would work "supended in the air", plus thanks for reminding me to get rid of air bubbles.

Raymond

--- In TekScopes@..., David <davidwhess@> wrote:

Concerning your point 4, with the presumably bad high voltage
multiplier disconnected, shouldn't the high voltage test point settle
at -2975 volts?

That makes me think something failed in the regulation circuit built
around Q1201, Q1206, and Q1214 including feedback divider R1245.

If the high voltage regulator ran away then maybe it damaged the high
voltage multiplier instead of the reverse.

As to building one with discrete parts, that is what I would do. The
esoteric thing that comes to mind other than standard high voltage
construction methods is the use of a vacuum to remove air from any
potting mixture. I would build the circuit supported in air by its
three external connections without using perforated board and then pot
it.


Re: Tek 2211 - Intermitent information display issues.

 

x10 vertical magnification (500uV/div = 5mV/div x 10) is turned on by
pulling the vertical CAL control straight out. Bandwidth is lowered
from 50 MHz to 5 Mhz when x10 vertical magnification is on so this can
also be used to lower the vertical bandwidth even if the higher
sensitivity is not needed.

On Wed, 24 Apr 2013 21:02:03 -0000, "acousticbruce"
<acousticbruce@...> wrote:

Yes 500uV/div is nice. I wish my 200Mhz LeCroy had this. I didn't realize this scope had this setting though. Ill have to look at it when I get home. I will check this out and see how much the service manual is.

--- In TekScopes@..., David <davidwhess@...> wrote:

The 2211 is suppose to be nice for audio because of the 500uV/div
sensitivity.

I have seen this problem before in my 7854 which I easily repaired. I
would look for a partial open in the vertical readout circuit chain
between the readout board and the vertical amplifier. My first
suspect would be the trimmer potentiometer which controls the vertical
readout gain but it could also be a bad solder joint or bad resistor.
The trimmer potentiometer was the bad part on my 7854.

I have never seen a service manual for the 2211 but you may be able to
find the vertical readout gain adjustment without it. ArtekManuals
has a 2211 service manual available though.

On Wed, 24 Apr 2013 16:45:07 -0000, "acousticbruce"
<acousticbruce@...> wrote:

This 2211 seems to perform well in all areas other then the info display. The problems are intermittent and seem to happen on their own. I cannot cause the display to mess up by messing with the scope. It seems to happen intermittently regardless of working with the scope or not.

Here is a very simple youtube video that gets right to the point. At the start you see a great display and info in the correct spot. Then about 1:35 you see the screen information slide up in proper position.

http://youtu.be/BWkOQ1PhFVI

I cannot find a service manual for the life of me. What do you think the problem is? Have you seen this type of thing before?


TDS 694 waveforms problems

Gennady
 

Hello group.

I am building half-bridge inverter and trying to check waveforms wit my Tek.

It looks perfectly fine while checking signal on gates of the FETs
please see album "Tek waveforms" - picture TEK00011

And when I am trying to see signal across the resistive load I have next - TEK0012 - it is heavily distorted and with wrong voltage.
For reference I am adding picture from my old trustful analog scope - Lider.

Your insight will be very appreciated.
Gene.


Re: Tek 2211 - Intermitent information display issues.

acousticbruce <acousticbruce@...>
 

Yes 500uV/div is nice. I wish my 200Mhz LeCroy had this. I didn't realize this scope had this setting though. Ill have to look at it when I get home. I will check this out and see how much the service manual is.

--- In TekScopes@..., David <davidwhess@...> wrote:

The 2211 is suppose to be nice for audio because of the 500uV/div
sensitivity.

I have seen this problem before in my 7854 which I easily repaired. I
would look for a partial open in the vertical readout circuit chain
between the readout board and the vertical amplifier. My first
suspect would be the trimmer potentiometer which controls the vertical
readout gain but it could also be a bad solder joint or bad resistor.
The trimmer potentiometer was the bad part on my 7854.

I have never seen a service manual for the 2211 but you may be able to
find the vertical readout gain adjustment without it. ArtekManuals
has a 2211 service manual available though.

On Wed, 24 Apr 2013 16:45:07 -0000, "acousticbruce"
<acousticbruce@...> wrote:

This 2211 seems to perform well in all areas other then the info display. The problems are intermittent and seem to happen on their own. I cannot cause the display to mess up by messing with the scope. It seems to happen intermittently regardless of working with the scope or not.

Here is a very simple youtube video that gets right to the point. At the start you see a great display and info in the correct spot. Then about 1:35 you see the screen information slide up in proper position.

http://youtu.be/BWkOQ1PhFVI

I cannot find a service manual for the life of me. What do you think the problem is? Have you seen this type of thing before?


Re: Tek 2235 No Horizontal B sweep.

acousticbruce <acousticbruce@...>
 

You know I am going to hit myself if it was because I didnt set the B sec/div. I really thought I tested this because I do understand what B mode is for. So I will respond again soon with what I find.

--- In TekScopes@..., "vdonisa" <vdonisa@...> wrote:

You can beat me but I can't figure what the purpose of your test is. That control is used to provide a "magnifier" of a small segment of the main waveform. The normal way I use it is to pull the time base knob and rotate it CW, with the "Mode" button on "ALT". At that moment a segment of the existing waveform is displayed "intensified" (brighter) and the brighter segment is shown magnified as a second waveform. Using the B trigger level and B delay time controls, you can move the "intensified" area along the main waveform to select which particular area you want to magnify.
Switching the "mode" control to "B" will display only the "magnified" area (the main waveform disappears from the screen).

--- In TekScopes@..., "acousticbruce" <acousticbruce@> wrote:

That control did not fix the problem. I did double check and try it fully clockwise among other positions. I really think it is a problem with the scope. I am open to ideas.

--- In TekScopes@..., David <davidwhess@> wrote:

Check the setting of the B trigger level control (top right corner
below VAR HOLDOFF). It can either be set to "runs after" or "triggers
after". In most cases you want it set all the way clockwise to "runs
after".

On Wed, 24 Apr 2013 16:36:28 -0000, "acousticbruce"
<acousticbruce@> wrote:

I have this 2235 that seems to be working for well on everything except the horizontal B sweep. What I did is put it in B mode and you can see to the left of the CRT some light. So I moved the horizontal position until you saw a possible triggered wave. I slowed the time down and you can see the beam moving up and down as suspected. I figured it is not sweeping. I am unsure if it will trigger either because I need it to sweep.

Here is a youtube video of me getting right to the point and showing this issue.

http://youtu.be/IfTkgZURFi0

This video gets right to the point and is short. I show a working sweep in A horizontal then flip to B horizontal.

What do you guys think?


465B, vs. 2235, et al...which to get?

 

This general family of dual trace 100Mhz scopes were always the workhorses of Tek's portable line up, and are really good performers if they have been well cared for.

by 2013, all 465B's will be pretty old, so some cap changes, bit of internal clean up, etc. will be in the cards. Dis-assembly of this model to the board level for PSU repairs is a bit cumbersome, and the unit is quite heavy, about 3x the 2235 weight. It requires a fan, which by this date is sometimes troublesome. Still, one of my all time faves, but don't get a non-B unit, many additional problems, and a much older design. late serial number B's are a great buy if working.

2235's (there are mil and regular and A versions) are great scopes in terms of performance, and weight, and easy to service EXCEPT for the front panel area. This is their great failing, getting to the attenuators, or anything like a front panel pot, switch, etc. is a total nightmare. The HV switcher also gives some trouble. however, today if I had equal 465B and 2235's to pick from, it'd take the newer 2235/A type. They are more fixable, and great performers, but I dread working in that front area. their CRTs are also sharper, they do not have that goofy CRT gun mesh that's in the 465-series. also no fan.

it's very important to remember that the specific mandate of the 2200 series was to be cost-competitive with import scopes, which in general they are. they only downside is that build quality is not as gold plated and robust as the 400 series. all switches in particular are not Tek custom parts, but low end, off the shelf items. pots are still very good.

I really like the super-rugged 2335 or 2336 dual trace 100Mhz portables if you can find a good one. think of these scopes as shrunk in a dryer and sealed in a can, and you have it, everything is a bit smaller, but built like a tank. the military bought a lot of them, so there's many around, just watch out for those pesky lid latches, they are usually broken or missing.

just my $0.02 worth
all the best,
walter
sphere research corp.
http://www.sphere.bc.ca/test/index.html


Re: Looking for Tektronix 419 scopes and parts

David DiGiacomo
 

On Wed, Apr 24, 2013 at 1:19 PM, altairjump <altairjump@...> wrote:
Hi,
I'm looking for Tektronix 419 oscilloscopes and parts. Also looking for a maintanence manual( I found the operations manual on BAMA) The scopes can be dead or alive for I need parts to rebuild two I have. Please let me know if anyone has any. I will travel to your location if you have complete scopes.
Do you mean 491, 519, or ????


Re: 2236 a or not to a?

Jerry Barr
 

thanks i will look again/ what are the normal probe impedances?  1meg  i havent messed with electronics in twenty +yrs  but its beginning to come back
 
Jerry KJ6NTL

From: vdonisa
To: TekScopes@...
Sent: Wednesday, April 24, 2013 1:29 PM
Subject: [TekScopes] Re: 2236 a or not to a?
 
The 2236A is a later version.

Unfortunately I don't know what the procedure to remove that board is. Sometimes it's easier than it seems at first sight. Sometimes not.

--- In mailto:TekScopes%40yahoogroups.com, Jerry Barr wrote:
>
> well now stupid has set in/ the top board i referred to in a prior post is the counter multimeter board i thought it was the main board but it is hinged and there are other boards below it but it appears u have to take the whole front panel off to tilt it  up on its hinges  but where is the a u refer too the scope only says 2236 or is that a later version
>
>
> Jerry KJ6NTL
>
> From: vdonisa
> To: mailto:TekScopes%40yahoogroups.com
> Sent: Wednesday, April 24, 2013 1:00 PM
> Subject: [TekScopes] Re: 465B: to buy or not? what is it worth?
>
>  
> The dmm is an additional board.... I'm pretty sure the 2235A uses the same mainboard PCB as 2236A... the difference is that in the 2235A a few components are not installed, and you can see "2236A only" printed there.
>
> --- In mailto:TekScopes%40yahoogroups.com, Jerry Barr wrote:
> >
> > it seems from my vague recolection the board for the dmm is incorp on the main board and the whole front panel has to come off to service the  power supply as
> >
> > the main board is hinged but to get it opened up u need to remove the front panel cause the controls are in the way i only checked the b volts from the bottom  of the ps board
> > still havent a hv probe/so put it back togeather till i get it
> > Jerry KJ6NTL
> >
> > From: vdonisa <vdonisa@>
> > To: mailto:TekScopes%40yahoogroups.com
> > Sent: Wednesday, April 24, 2013 12:33 PM
> > Subject: [TekScopes] Re: 465B: to buy or not? what is it worth?
> >
> > 
>


Re: 2236 a or not to a?

 

The 2230 is the same way with the top board. You have to pull the
front panel push button switches apart before you can tilt it out of
the way.

The "main" board is the large one along the bottom of the oscilloscope
which contains the power supply section in one corner. That board is
shared among a number of the 22xx series with just parts differences.

On Wed, 24 Apr 2013 13:20:44 -0700 (PDT), Jerry Barr
<kj6ntl@...> wrote:

well now stupid has set in/ the top board i referred to in a prior post is the counter multimeter board i thought it was the main board but it is hinged and there are other boards below it but it appears u have to take the whole front panel off to tilt it  up on its hinges  but where is the a u refer too the scope only says 2236 or is that a later version

Jerry KJ6NTL

From: vdonisa <vdonisa@...>
To: TekScopes@...
Sent: Wednesday, April 24, 2013 1:00 PM
Subject: [TekScopes] Re: 465B: to buy or not? what is it worth?

 
The dmm is an additional board.... I'm pretty sure the 2235A uses the same mainboard PCB as 2236A... the difference is that in the 2235A a few components are not installed, and you can see "2236A only" printed there.

--- In mailto:TekScopes%40yahoogroups.com, Jerry Barr <kj6ntl@...> wrote:

it seems from my vague recolection the board for the dmm is incorp on the main board and the whole front panel has to come off to service the  power supply as

the main board is hinged but to get it opened up u need to remove the front panel cause the controls are in the way i only checked the b volts from the bottom  of the ps board
still havent a hv probe/so put it back togeather till i get it
Jerry KJ6NTL


Re: HV Multiplier defective in 7603?

raymonddompfrank <r.domp.frank@...>
 

I thought it had to be something like that, Albert..

Raymond

--- In TekScopes@..., "Albert" <aodiversen@...> wrote:

You're right, I have been busy with 5xx 'scopes lately and simply forgot that the 76xx is further transistorized.
Albert

--- In TekScopes@..., David <davidwhess@> wrote:

There are no tubes other than the CRT in the 7603. The high voltage
is regulated from the cathode voltage test point so except for
overshoot in the feedback loop, it should never exceed, um, -2975
volts in this case. Excessive current through the high voltage
multiplier could pull it down (toward zero) but never pull it up.


Hi Raymond,

For how long did you measure that -4kV? During startup the multiplier puts (considerable?) load on the oscillator since the internal caps and the CRT anode have to be charged. Without that load the HV can increase faster. It might be that the oscillator tube heats up quicker than the feedback tube(s), leading to excessive HV until the feedback comes in.

Albert

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